Refrigeration



Aug. 39, 1947. A. R. THOMAS 2,426,069

REFRIGERATION Filed Oct. 25. 1944 INV NTOR I 6 7 ATTORNEY Patented Aug. 19, 1947 REFRIGERATION Albert R. Thomas, deceased, late of Evansville, Ind., by The National City Bank, administrator, Evansville, Ind, assignor to Servel, Inc., New York, N. Y., a corporation of Delaware Application October 25, 1944, Serial No. 560,213

19 Claims. (Cl. 62-419 The present invention relates to improvements in absorption refrigeration systems and more particularly to apparatus for transferring noncondensible gases from one part of the system to another part thereof.

While the apparatus of the present invention may be applied to any two-pressure absorption refrigeration system it is particularly adapted for use with a system of the type illustrated and described in the prior patent to Thomas et al., No. 2,282,503, entitled Refrigeration. The absorption refrigeration system illustrated in the prior patent operates in a partial vacuum and utilizes water as a refrigerant and a saline solution as an absorbent. In such a refrigeration system non-condensible gases may accumulate in the various elements of the system which must be purged periodically. The exact cause of the generation of such non-condensible gases or the place where such gases are generated is not fully understood but the gases appear in all parts of the system and accumulate in the condenser and absorber. As the condenser operates at a higher pressure than the absorber the non-condensible gases may be purged more easily from the con-' denser than from the absorber. Furthermore, the presence of such non-condensible gases in the absorber decreases the emciency of the refrigeration system to a greater degree than their presence in the condenser.

One of the objects of the present invention is to provide apparatus in an absorption refrigeration system for continuously withdrawing noncondensible gases from the low pressure side of the system and transferring them to the high pressure side of the system.

Another object is to provide apparatus of the type indicated which utilizes vaporized refrigerant in a Venturi tube to evacuate non-condensible gases from the absorber and transfer them to the condenser.

Another object is to provide apparatus of the type indicated which operates to vaporize refrigerant continuously and maintain the refrigerant vapor at a predetermined constant pressure.

Another object is to provide apparatus of the type indicated in which the pressure of the refrigerant vapor is maintained constant by a balancing column of liquid refrigerant of predetermined height.

Still another object of the invention is to provide apparatus of the type indicated which is of simple construction and efllcient in performing its intended function. 7

These and other objects will become more apparent from the following description and drawing. It is to be expressly understood, however, that'the drawing is for the purpose of illustration only and not a definition of the limits of the invention, reference being had for this purpose to the appended claims. In the drawing, the single figure is a'diagrammatic view of an absorption refrigeration system incorporating the novel features of the present invention.

shown as applied to a two-pressure absorption refrigerating system similar to that illustrated X and described in the prior Thomas et a1. patent, referred to above. In a system of this type liquid refrigerant such as, for example, water is introduced into the upper part of an evaporator or cooling element 10 from a condenser H through a path of flow including a U-shaped tube l2 and a chamber I3. The, liquid refrigerant evaporates in evaporator [0 with consequent absorption of heat from the ambient, such as a stream of air flowing over the exterior surface of the tubes l6 and fins l5 of the evaporator. The refrigerant vapor formed in evaporator l0 flows to an absorber HS in which the vapor is absorbed into a liquid absorbent such as, for example, a solution of lithium chloride or lithium bromide.

The absorption liquid enriched with refrigerant is conducted from the absorber IE to a generator I! in a path of flow including a conduit l8, liquid heat exchanger l9, conduit 20, vessel 2|, and

conduit 22. Within the generator I! are disposed a plurality of riser tubes 23 enclosed by an outer shell forming a chamber to which steam is sup-.

plied through a conduit 24 from a suitable source of supply. The heating of the riser tubes 23 by the steam causes refrigerant vapor to be expelled from the absorbent and the expelled vapor is effective to raise the absorbent liquid by gas or vapor-lift action.

The expelled vapor passes from the upper ends of the riser tubes 23 into a vapor separator 25 and thence flows through a conduit 26 to the condenser II in which the vapor is liquefied. Liquid refrigerant formed in'condenser ll flows into a sump 21 and from the sump flows into a lateral branch-conduit 28 and through the U-shaped tube 12 to the .upper part of the evaporator ID, as explained above, to complete the refrigerating cycle.

The raised absorption liquid from which refrigerant vapor has been expelled is conducted from the upper part of the generator I! to absorber Hi to absorb refrigerant vapor, this liquid being conducted to the absorber in a path of flow Referring tothe drawing, the invention is" including a conduit 29, liquid heat exchanger l9 and conduit 30. The heat liberated by absorption of refrigerant vapor in absorber I6 is taken up by a cooling medium such as, for example, Water which flows upward through vertically disposed banks of pipes 3| in the absorber. The cooling water is introduced into the lower end of the banks of pipes through a conduit 32 and'is discharged from the upper ends of the 'banks of pipes through a conduit 33. The conduit 33 is connected to condenser H o that the cooling water also may be utilized to effect cooling of the condenser II. The cooling water is discharged from condenser ll through a conduit 34.

The system operates in a partial vacuum with generator H and condenser ll operating at one pressure and evaporator l and absorber l6 operating at a lower pressure. The pressure differ.- ential between the high and low pressure sides of the system is maintained by a liquid column in the up leg of the U-shaped tube I l-between the condenser II and evaporator l0 and a liquid column in the conduit l8 connecting the absorber l6 and the heat exchanger I9; A liquid column is also provided in the conduit 3!) connecting the heat exchanger I6 and absorber 16. The liquid level in the U-shaped tube i2 is indicated by the reference character 1:; thej liquid level in the vessel 2| connected to the conduit l8 through the heat exchanger i9 is indicated by the reference character 1 and the liquid level in the conduit 29 connected to the conduit 30 through the heat exchanger [9 is indicated by the reference character z.

During operation of the refrigeration system non-condensible gases may accumulate in the various elements thereof. These non-condensible gases are probablyjormed by the chemical action of the fluids with the metallic parts of the system. The gases in the condenser tend to accumulate adjacent the outlet sump 21 and down-leg 4| and an up-leg 42 connected by a may to some extent be transferred through the U-shaped tube l2 to the upper part of the evaporator I 0. Such gase in the evaporator III are swept into the absorber l6 by the refrigerant as it flows into the absorber at high velocity. The gases then accumulate in a layer at the bottom of the absorber l6. Thus the non-condensible gases accumulate adjacent the outlet of the condenser II and at the bottom and center of the absorber l6 and blanket off that portion of the condenser or absorber which they cover. v

As the condenser H operates at a higher pressure than the absorber l6 the non-condensible gases may be withdrawn from the condenser with greater ease than from the absorber. For this reason an exhaust pipe 36 is connected between the condenser at a point adjacent its outlet and a suitable exhaust pump, not herein shown. The

non-condensible gases are purged periodically from the condenser by the exhaust pump and preferably a manually operable stop valve 31 is provided in the exhaust pipe 36. As the noncondensible gases are purged from the condenser H it is necessary to provide some means for transferring the gases from the absorber l6 to the condenser. Furthermore, due to the difference in pressure in the condenser and absorber the same amount of the non-condensible gas will blanket off a greater portion of the absorber than of the condenser. As a result the accumulation of the gases in the absorberdecrease the emciency of the refrigeration system to a greater degree than when present in the condenser. It

is, therefore, desirable to transfer the non-conloop at their lower ends. The upper end of the down-leg 4| of the U-tube 40 is connected to the bottom of the sump 21 at the outlet from the condenser II. The end of the up-leg 42 of the U- tube 40 extends into an annular chamber 43 at one end of a Venturi tube 44. The end of the Venturi tube 44 is welded or otherwise sealed to the sides of the up-leg of the U-tube 40 adjacent its upper end and the Venturi tube tapers inwardly around the end of the U- tube to provide a Venturi throat, 45. The Venturi tube 44 beyond the throat 45 gradually increases in diameter and its opposite end is connected to the conduit 26 extending between the generator I] and condenser I 1. Connecting the chamber 43 in the Venturi tube 44 and the interior of the absorber I6 is a conduit 46 which extends through the side wall of the absorber with its end positioned at the center and adjacent the bottom thereof where the non-condensible gases accumulate.

The lower looped end of U-tube 40 may be heated by any suitable means to vaporize liquid refrigerant therein. In the embodiment of the invention illustrated in the drawin the lower end of the up-leg 42 of the U-tube 40 has a number of helical coils 41 surrounding the base of the generator I! in heat conducting contact therewith which constitutes a flash boiler for continuously vaporizing liquid refrigerant. While the apparatus is described as comprising separate parts it is in effect a continuous U-tube having its opposite ends connected at opposite sides of the condenser. with a down-leg 4| connected to receive condensate from the condenser, an up-leg 42 having a Venturi throat 45 therein, a chamber 43 adjacent the Venturi throat connected to the absorber I6 through the conduit 46 and heating coils 41 at the lower end of the up-leg 'in heat conducting relationship with the base of the generator H. The construction of the apparatus having been described in detail its mode of operation is explained as follows.

For purposes of description let it be assumed that no heat is being supplied to the generator and the refrigeration system is inoperative. The opposite legs 4! and 42 of the U-tube 40 will have columns of liquid refrigerant therein of equal height. When steam is supplied to the generator I! through the conduit 24 the refrigerant will be vaporized in the vertical riser tubes 23 and will rise through the vapor separator 25 and conduit 26 to the condenser II, The refrigerant vapor will be condensed in the condenser H and flow by gravity into the sump 21 and down-leg 4| of the U-tube 40.

Simultaneously with the vaporization of the refrigerant in the generator I! the liquid refrigerant in the coils 41 at the lower end of the up-leg 42 of the U-tube 40 will be vaporized by heat conduction from the generator. Such vaporized refrigerant in the coils 41 will expand and move upwardly in the up-le 42 to displace the liquid refrigerant therein and cause it to spill over into the chamber 43 and flow through the conduit 46 to the absorber l6. This action will for heating the generator to expel refrigerant arranged to receive liquid refrigerant from one,

of the high pressure elements of the system, means for heating the boiler to vaporize the liquid refrigerant therein, and a device utilizing the refrigerant vaporized in the boiler for withdrawing non-condensible gases from an element of the low pressure group and transferring the gases to an element of the high pressure group.

3. In an absorption refrigeration system of the type having one group of elements including an evaporator and absorber operable at low pressure and another group of elements including a generator and condenser operable at a higher pressure, means for maintaining the pressure differential between the groups of elements, means for heating the generator to expel refrigerant vapor from absorption solution therein, a boiler arranged to receive liquid refrigerant from one of the high pressure elements of the system,

means for heating the boiler to vaporize the 4. In an absorption refrigeration system of the type having an absorber operable at low pressure and a condenser operable at a higher pressure with means for maintaining the pressure differentialbetween the condenser and absorber, the

combination with said condenser and absorber of a boiler arranged to receive liquid refrigerant from the condenser, means for heating the boiler to vaporize, the liquid refrigerant therein, and a Venturi tube utilizing the refrigerant vaporized in the boiler and connected to withdraw non-condensible gases from the absorber and transfer the gases to the condenser.

5. In an absorptionrefrigeration system of the type having one group of elements operable at low pressure and another group of elements operable at a higher pressure with means for main taining the pressure differential between the groups of elements, the combination with said system of a boiler, a conduit arranged to supply liquid refrigerant from one of the high pressure elements of the system to the boiler and maintain a column of liquid therein to produce a pressure in the boiler higher than the pressure in the remainder of the system, means for heating the boiler to vaporize the liquid refrigerant therein, a Venturi tube connected to receive vaporized refrigerant from the boiler, and conduits connecting the Venturi and elements of the high and low pressure groups, said Venturi tube utilizing the vaporized refrigerant for withdrawing non-condensible gases from the low pressure group through one of the conduits and transferring the gases to an element of the high pressure group through the other conduit.

6. In an absorption refrigeration system of the type havingone. group of elements operable at low pressure and another group of elements operable at a higher pressure with means for maintaining the pressure differential between the groups of elements, the combination with said sys tem of a depending U-tube connected at its opposite ends to elements of the high pressure V 8 tube, a conduit connected. to an element of the low pressure group, and a device utilizing the vaporized refrigerant in the U-tube for withdrawing non-condensible gases from the element of the low pressure group through the conduit and transferring the gases to an element of the high pressure group.

'7. In an absorption refrigeration system of the type having an absorber operable at low pressure and a condenser operable at a higher pressure with means for maintaining the pressure differential between the condenser and absorber, the combination with said condenser and absorber of a U-tube connected at itsopposite ends to the opposite sides of the condenser, said U-tube being arranged to receive liquid refrigerant at one end and discharge refrigerant vapor from its opposite end, means for vaporizing the liquid refrigerant in the U-tube, a conduit connected to the absorber, and a device utilizing the vaporized refrigerant in the U-tube to withdraw noncondensible gases from the absorber through the conduit and transfer'the gases to the condenser. -8. In an absorption refrigeration system' of the type having one group of elements operable at low pressure and another group of elements operable at a higher pressure with means for maintaining the pressure differential between the groups of elements, the combination with said system of a U-tube connected at its opposite ends to elements of the high pressure group, said U-tube being arranged to receive liquid refrigerant at one end and discharge refrigerant vapor 7 .from its opposite end, means for vaporizing the group, said U-tube being arranged to receive liquid refrigerant in the U-tube, a conduit connected to an element of the low pressuregroup, and a Venturi tube utilizing the vaporized refrigerant in the U-tube to withdraw non-condensible gases from the element of the low pressure group through the conduit and transfer the gases to an element of the high pressuregroup. 9. In an absorption refrigeration system of the type having one group of elements operable at low pressure and another group of elements operable at a higher pressure with means for maintaining the pressure differential between the groups of elements. the combination with said system of a U-tube connected at its opposite ends to elements of the high pressure group, said U-tube being arranged to receive liquid refrigerant at one end and discharge refrigerant vapor from its opposite end, means for, vaporizing the liquid refrigerant in the U-tube, a conduit connecting the U-tube and an element of the low pressure roup, and a Venturi throat in. the U-tube utilizing the vaporized refrigerant therein to Withdraw non-eondensible gases from the element of the low pressure group through the conduit and transfer the gases to an element of the high pressure group.

10. In an absorption refrigeration system of the type having an absorber operable at low pressure and a condenser operable at a higher pressure with means for maintaining the pressure differential between the condenser and absorber, the combination with said condenser and absorber of a U-tube connected at its opposite ends to the opposite sides of the condenser, said U-tube being arranged to receive liquid refrigerant from the condenser at one end and discharge refrigerant vapor to the condenser at its opposite end, a Venturi throat in the U-tube, and a conduit connecting the Venturi throat and absorber, said venturi utilizing the vaporized refrigerant in the U-tube to withdraw non-condensible gases from the abcontinue until the liquid refrigerant in the uD-leg 42 has been completely displaced by the vaporized refrigerant. The column of liquid refrigerant in the down-leg 4| of the U-tube 40 will tend to flow into the coils 47 to be vaporized therein. The feeding of the liquid refrigerant to the coils 41, however, will be opposed by the pressure of the vaporized refrigerant in the up-leg 42. Thus the pressure of the vaporized refrigerant in the upleg 42 is balanced and maintained by the column of liquid refrigerant in the down-leg 4|. As the refrigeration system continues to operate more condensate from the condenser will be fed to the sump 21 which increases the height of the liquid column in the down-leg 4| until its level is raised to the level of the lateral branch-conduit 28 where it over-flows into the U-tube |2 connected to the evaporator It). It will be observed, there fore, that the lateral branch conduit 28 will maintain a column of liquid in the down-leg 4| of the U-tube 40 of a predetermined height as indicated by the reference character h. With a column of liquid in the down-leg 4| of a predetermined height the vaporized refrigerant in the up-leg 42 will be maintained at a pressure corresponding to the height of the liquid column.

The vaporized refrigerant in the up-leg 42 of the U-tube 40 will escape from its open end under pressure and pass through the Venturi throat 45. The flow of refrigerant vapor through the Venturi throat 45 entrains the media in the chamber 43 to evacuate the latter, the vaporized refrigerant and entrained media flowing through the Venturi tube 44 to the conduit 26 and into the condenser The evacuation of the chamber 43 will continue until the pressure therein is less than the pressure in the absorber Hi, When the pressure in the chamber 43 is less than the pressure in the absorber IS the non-condensible gases adjacent the end of the conduit 46 will be drawn therethrough and into the chamber and pass through the Venturi tube 44 to the conduit 26 and into the condenser During normal operation of the refrigeration system the liquid refrigerant will be continuously vaporized in the heating coils 41 at the lower end of the up-leg 42 of the U-tube 40 and the vaporized refrigerant will be forced under pressure through the Venturi tube 44 to withdraw non-condensible gases from the absorber l6 continuously and transfer the gases to the condenser I. Periodically the non-condensible gases will be purged from the condenser by means of the vacuum pump (not shown) which operates to evacuate the exhaust pipe 38 connected to the condenser until the pressure in the latter is lower than the pressure in the condenser. The stop valve 31 in the exhaust pipe 36 then will be opened to connect the interior of the condenser H to the vacuum pump to withdraw the non-condensible gases. At the completion of a purging operation the stop valve 31 is closed. I

It will be understood that the U-tube 40 will be so constructed and arranged as to adapt it for the conditions of the particular refrigeration system to which it is applied. For instance, the diameter of the up-leg 42 of the U-tube '40 must be so limited as to maintain the pressure of the vaporized refrigerant while providing a suflicient volume of vapor discharged from its end to create the desired vacuum in the chamber 43. It also will be understood by those skilled in the art that a nozzle may be provided at the upper end of the up-leg 42 if such a nozzle is found necessary. A specific example of the' operating conditions of the particular absorption refrigeration system to which the present invention is shown applied is described as follows. The absolute pressure normally occurring in the condenser is one pound per square inch (la /sq. in.) while the absolute pressure occurring in the absorber H3 is one-tenth of a pound per square inch (.1#/sq. in.). It has been found that by maintaining a refrigerant vapor pressure in the upleg 42 of the U-tube 40 of four pounds per square inch (4#/sq. in.) absolute a sufficiently high vacuum may be maintained in the chamber 43 to continuously withdraw non-condensible gases from the absorber 16. In order to maintain a pressure of the refrigerant vapor of four pounds per square inch absolute a liquid column six feet high must be maintained in the down-leg 4| of the U-tube. This liquid column i maintained in the down-leg 4| by arranging the lateral branchconduit 28 a distance of six'feet above the bottom of the U-tube 40. The six foot head of liquid refrigerant in the down-leg 4| corresponds to a pressure of three pounds per square inch (3#/sq. in.) which in addition to the one pound per square inch occurring in the condenser gives a total pressure of the refrigerant vapor of four pounds per square inch absolute.

It will now be observed that the present invention provides an apparatus for continuously transferring non-condensible gases from the low pressure side of the system to the high pressure side of the system. It will further be observed that the invention utilizes vaporized refrigerant at apredetermined constant pressure in a Venturi tube to withdraw'the non-condensible gases from the low pressure absorber and transfer them to the high pressure condenser. It will still further be observed that the present invention provides a novel construction of apparatus for maintaining a column of liquid refrigerant of a predetermined height to balance the vaporized refrigerant to maintain the latter at a predetermined constant pressure.

While a preferred embodiment of the invention is herein shown and described as applied to a particular absorption refrigeration system, it will be apparent to those skilled in the art that the invention may be applied to other systems and that various modifications and changes may be made in the construction and arrangement of the parts thereof without departing from the spirit or scope of the invention.

What is claimed is:

1. In an absorption refrigeration system of the type which operates in a partial vacuum and utilizes water as a refrigerant and salt solution as an absorbent and in which non-condensible gases may occur, said system having one group of elements operable at low pressure and another group of elements operable at a higher pressure, means including liquid columns for maintaining the pressure differential between the groups of elements, and apparatus utilizing a portion of the refrigerant for transferring non-condensible gases from an element of the low pressure group to an element of the high pressure group in said system, said apparatus being connected to receive refrigerant from and return the refrigerant to said system.

2. In an absorption refrigeration system of the type having one group of elements operable at low pressure and another group of elements including a generator operable at a higher pressure, means for maintaining the pressure differential between the groups of elements, means sorter through the conduit and transferathe'gases to the condenser.

11. In an absorption refrigerationsystem Of the type having one group of elements operable at low pressure and another group of elements operable at a higherpressure with means for mainliquid column in the first leg, and a device utiliz ing the vaporized refrigerant in the U-tube for transferring non-condensible gases from an element of the low pressure group to an element of the high pressure group.

12. In an absorption refrigeration system v the type having one group of elements operable at low pressure and another group of elements porized refrigerant in the U-tube for wlthdrawing non-condensible gases from the element of the low pressure group through the conduit and transferring the gases to an element or the high pressure group.

15. In an absorption refrigeration system of th type having one group of elements operable at low pressure and another group .of elements operable at a higher pressure with means for maintaining the pressure differential between the groups of e1ements,-'a U-tube' connected ,at its opposite ends to elements of the high pressure group, said U-tube being arranged to receive liquid refrigerant continuously at one end to maintain a column of liquid of predetermined height in one leg thereof, means for vaporizing the liquid refrigerant at the lower end of the U- operable at a higher pressure with means for refrigerant, said branch conduit maintaining a liquid column in one leg of the U-tube of .a predetermined constant height, means for vaporizing the liquid refrigerant at the lower end of the U- tube to maintain vapor in the other leg of the U- tube at a pressure corresponding to the height of the liquid column in the first leg, and a device utilizing the vaporized refrigerant in the U-tube for transferring non-condensible gases from an element of the low pressure group to an element of the high pressure group.

13. In an absorption refrigeration system of the type having an absorber operable at low pressure and a condenser operable at a higher pressure with means for maintaining the pressure differential between the condenser and absorber, a U-tube connected at its opposite ends to the opposite sides of the condenser, said U-tube being arranged to receive liquid refrigerant continuous- 1y at one end to maintain a column of liquid of predetermined height in one leg thereof, means for vaporizing the liquid refrigerant at the lower end of the U-tube to maintain vapor in the other leg thereof at a, pressure corresponding to the height of the liquid column in the first leg, and a device utilizing the vaporized refrigerant in the U-tube for transferring nomcondensible gases from the absorber to the condenser.

14. In an absorption refrigeration system of the type having one group of elements operable at low. pressure and another group of elements operable at a higher pressure with means for maintaining the pressure differential between the groups of elements, a U-tube connected at its opposite ends to elements of the high pressure group, said U-tube being arranged to receive liquid refrigerant continuously at one end to maintain a column of liquid of predetermined height in one leg thereof, means for vaporizing the liquid refrigerant at the lower end of the U-tube to maintain vapor in the other leg thereof at a, pressure corresponding to the height of the liquid column in the first leg, a conduit connected to an element of the low pressure group, a Venturi tube connected to the conduit and utilizing the vatube to 'm'aintainvapor in the other leg at a pressure corresponding to the height of the liquid column in the first leg, a Venturi throat in the second leg of the U-tube, and a conduit connecting an element of the low pressure group to the Venturi throat, said vapor in the leg of the U-tube passing through'the Venturi throat to withdraw non-condensible gases from the ele- I ment of the low pressure group and transfer the gases to an element of the high pressure group.

16; In an absorption refrigeration system of the type having an absorber operable at low pressure and acondenser operable at a higher pressure with means for maintainin the pressure differential between the groups of elements, a U-tube connected at its opposite ends to the opposite sides of the condenser, said U-tube being arranged to receive liquid refrigerant continuously from the condenser at one end to maintain a column of liquid of predetermined height in one leg thereof, means for vaporizing the liquid refrigerant at the lower end of the U-tube to maintain vapor in the other leg of the U-tube at a pressure corresponding to the height of the liquid column in the first leg, a Venturi throat in the second leg of the U-tube, and a conduit "connecting the absorber and Venturi throat, said vaporized refrigerant in the U-tube passing through the Venturi throat to withdraw noncondensible gases from the absorber through the conduit and transfer the gases to the condenser.

17. In an absorption refrigeration system of the time having an evaporator and absorber operable at low pressure and a generator and condenser operable at a higher pressure with means for maintaining the pressure differential therebetween, a U-tube connected at its opposite ends to the opposite side of the condenser, said U-tube being arranged to receive liquid refrigerant continuously at one end, a branch conduit adjacent the upper end of the U-tube for receiving liquid refrigerant and delivering it to the evaporator. said branch conduit maintaining a liquid column in the leg ofthe U-tube of a predetermined height, the lower end of the U-tube havin coils surrounding the base of the generator to vaporize the liquid refrigerant therein to maintain vapor in the other leg of the U-tube at a pressure corresponding to the height of the liquid column in the first leg, and a device utilizing the vaporized refrigerant in the U-tube for transferring non-condensible gases from the absorber to the condenser.

18. In an absorption refrigeration system of the type having an evaporator and absorber 0D- erable at low pressure and a generator and condenser operable at a higher pressure, conduits connecting the condenser and evaporator and the absorber and generator and arranged to maintain liquid columns therein to balance the differential in pressure, a U-tube connected at its opposite ends to the opposite side of thecondenser, said U-tube being arranged to receive liquid refrigerant continuously at oneend from the condenser, the conduit between the con- 7 denser and evaporator being connected to the U- tube adjacent its upper end to maintain a liquid column'in one leg thereof of a predetermined height, means for vaporizing the liquid refrigerant in the lower end of the .U-tube to maintain vapor in the other leg of the U-tube at a pressure corresponding to the height of the liquid column in the first leg, a Venturi throat in the second leg of the U-tube, and a conduit con necting the absorber and Venturi throat whereby -vaporized refrigerant passing through the Venturi throat operates to withdraw non-condensible gases from the absorber and transfer them to the generator. g

19; In an absorption refrigeration system of the type utilizing water as a refrigerant and a saline solution as an absorbent and operable in a partial vacuum, a generator, a condenser, an evaporator, an absorber, conduits connecting the generator, condenser, evaporator, and absorber to provide a closed circuit and arranged to provide pressure balancing liquid columns between the generator and condenser and evapo- 12 rator and absorber, a U-tube connected at its opposite ends to opposite sides of the condenser, said U-tube receiving'iiquid refrigerant at." one end'from the condenser to maintain a liquidcolumn therein, means for vaporizing the liquid refrigerant at the lower end of the U-tube to producerefrigerant vapor in the other leg thereof at a pressure corresponding to the height of the liquid column in the first leg, a Venturi throat in the second leg of the U-tube, and a conduit connecting the absorber and Venturl throat whereby the vaporized refrigerant passing through the venturi operates to withdraw noncondensible gases from the absorber and transfer the gases to the condenser.

THE NATIONAL CITY BANK, Administrator of the Estate of Albert R Thomas,

Deceased,

By JOHN N. EMIG,

Vice President.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 258,227 Gergens May 23, 1882 30 2,374,521 Anderson, Jr Apr. 24, 1945 

